Dipole radio sonde



May 31, 1960 R. o. ROBINSQN, JR

DIPOLE RADIO SONDE Filed Feb. 29, 1952 3 Sheets-Sheet 1 FIG. 2.

IN V EN TOR.

RALPH 0. ROB/N80,, JR; 7

BY X zQcQEM ATTORNEY May 31, 1960 R. o. ROBINSON, JR

DIPOLE RADIO SONDE Filed Feb. 29, 1952 lea 3 Sheets-Sheet 2 FIG.

INVENTOR.

F RALPH 0. ROB/NSOMJR.

BY M40196;

ATTORNEY May 31, 1960 R. o. ROBINSON, JR 2,939,130

DIPOLE RADIO SONDE File d Feb. 29, 1952 FIG. 6.

3 Sheets-Sheet 3 INVENTOR.

RALPH 0. ROBINSON, an:

ATTORNEY oscillator frequencies.

DIPOLE RADIO SONDE Ralph 0. Robinson, Jr.,

the United States of Secretary of the Navy Filed Feb. 29, 1952, Ser. No.274,110

15 Claims. (Cl. 343-7) Silver Spring, Md., assignor to America asrepresented by the especially such devices as are employed in aerialmissiles and projectiles) of the radio proximity fuze type have beenknown for some time. This invention relates to improvements in suchsondes.

Mathematical calculations based on data obtained from experimentalstudies made at very high frequencies with radio sondes having dipoleantennae and attached to fin stabilized rockets have indicated thepresence of objectionable multi-lobe radiation patterns at the desiredsonde It is believed that these undesirable radiation patterns are dueto the presence of the rocket body.

It is one of the principal objects of the present invention, therefore,to provide a radiating system and apparatus for use with missiles, suchas rockets and projectiles, which will generate a radiation patternunaffected by the presence of the body of the missile in the electricalfield.

Another object of the invention is to provide a radiating system andapparatus for a projectile which will greatly minimize multi-loberadiation patterns at the desired sonde oscillator frequencies.

To accomplish the reduction of multi-lobe radiation by the provision ofmeans constituted by a resonant circuit adjusted to present a highimpedance to radio frequency currents flowing from the innermost end ofthe dipole antenna in the rocket to the body of the rocket, is alsoanother object of the invention.

To provide a radio sonde and dipole antenna arrangement wherein theoscillator components are located between the radiating elements of thedipole, with the radiating element separating insulator, employedserving the 'dual function of rigidly supporting these elements andmounting the oscillator components so that they will be protected fromthe atmosphere elements and from mechanical shock due to handling andfiring, is still another principal object of this invention.

According to the present invention, a dipole sonde comprising anelectric dipole is mounted in the forward part of a projectile andparallel to the axis thereof. A lobe eliminator is then connectedbetween the main part of the projectile body and the nearest section ofthe dipole. By means of this arrangement, the radio frequency currentsin the body of the projectile are reduced to an absolute minimum, thusallowing the major portion of the radiation to emanate from the dipole.The dipole sections are so constructed that the oscillator circuitry andits power supply is contained within the antenna itself.-

The invention will be described by way of example 2,939,139 Patented May31, 1960 with reference to the accompanying drawings in which:

Fig. 1 is a plan view, on a reduced scale, of a rocket missile embodyingthe invention;

Fig. 2 is a enlarged fragmentary axial section of the missile shown inFig. 1, with a portion thereof containing a circuit diagram of theelectrical equipment;

Fig. 3 is a radiation pattern for a high powered radio sonde operatingon a given frequency range with conventional nose excitation;

Fig. 4 is a radiation pattern for a high powered radio sonde operatingon another frequency range with conventional nose excitation;

Fig. 5 illustrates radiation patterns for a dipole sonde operating on agiven frequency range both with and without the lobe eliminator; and

Fig. 6 shows a radiation pattern of another dipole sonde operating onanother frequency range and including a lobe eliminator.

invention.

In Fig. 1, there is shown a non-rotating, fin stabilized rocket 10incorporating the invention. It is to be understood, however, that theinvention is not limited in use with this type of missile but can beadapted and utilized with other types of missiles as Well as havingother applications unrelated to the ordnance field, such as permanentlyinstalled and mobile antennas.

Rocket 10 comprises a nose section 12, a dipole sonde 14, a lobeeliminator section 16, and the rocket motor section 18, including thefins 20 for stabilizing the rocket during flight, said rocket motorsection constituting the main body of the missile.

The dipole sonde 14 consists of an electric dipole of two sections 22and 24 mounted in the forward portion of rocket 10. Each element 22 and24 of the dipole sonde 14 is approximately 2%." in diameter and 5 /2"long in a typical embodiment. This permits the building of theoscillator circuit and its power supply (which will be describedpresently) within the dipole antenna 14 itself. The dipole antenna 14 isso designed that it will always be much shorter than a half wave lengthat the transmitted frequency.

Between dipole sections 22 and 24, as previously pointed out, there islocated the oscillator section 15 which contains a conventionaloscillator .circuit 26, including the oscillator coil 27 and oscillatortube 28. The oscillator coil 27 is usually mounted parallelto. the axisof the dipole sonde 14. This oscillator section 15 is housed within adipole separation polystyrene insulator 29 which extends between dipolesections 22 and 24, as best illustrated in Fig. 2.

The power, supply for the oscillator tube 28 is a conventional proximityfuze dry cell battery 30 which is enclosed within the dipole section 24of the dipole antenna 14 nearest the rocket motor 18.

Battery 3% includes two sections 32 and 34. Section 32 of the battery 30is used for applying the necessary filament voltage to filament 36 oftube 28, while battery section 34 is utilized for applying the platevoltage to plate 38 of tube 28.

The power supply battery 30 is so connected with a switch 39 that when ascrew element 40 is screwed into its holder 41 a sufiicient distance,electrical contact is made with contact element 42 so as to close thecircuit. when the circuit is closed, the plate and filament voltages areapplied to the oscillator tube 28. The plate voltage from batterysection 34 is applied to the oscillator tube plate 38 through conductor44 and a radio frequency choke 46, while the filament voltage frombattery section 32 is applied to filament 36 through conductor 48 andaradio frequency choke 50. A conductor 52 from the ranges.

filament 36'taps into oscillator coil 27 to divide it into two sections,the plate coil section 54 and the grid coil section 56. Oscillator coil27 usually consists of 2 turns ofnumber 18 wire, diameter and /zf long,

but not necessarily limited thereto. V i 1 Between plate 38 of theoscillator .tube. 28 and the plate coil 54 of oscillator coil 27, thereis located a stopping or isolating condenser 58 which is utilized toprevent short-circuiting of battery section 32. This condenser isusually of 100 mmf.

The dipole sonde 14 is excited by establishing an oscillating R.-F.potential between sections 22 and 24, said excitation being derived fromoscillator coil 27 by means of conductor 60 for section 22 and conductor'62 for section 24. The proper impedance matching is established bylocation of tap 110 relative to end 112 of coil 27. Grid 64 is connectedto section 24 by conductor 66;

As previously pointed out, a lobe eliminator 70 is.

located in section 16 between dipole section 24 and'the main body of therocket motor section 18. Lobe eliminator 70 consists of a parallelresonant circuit including a variable capacitor 72 and an inductancecoil 74. In the present embodiment, capacitor 72 is usually between -2and 5 mmf. capacity, while coil 74 usually consists of 2 /2 turns ofnumber 18 wire of ,3 diameter and A" long, although not necessarilylimited thereto. Section 16 is insulated from rocket motor section 18and dipole section 24 by means of a polystyrene insulator 80.

As previously indicated, lobe eliminator 70 is a resonant circuit. Thiscircuit is adjusted to present a high impedance to radio frequenciescurrents flowing from the dipole section 24 to the body of the rocketmotor 18.

The magnitudes of inductance and capacity chosen for the lobe eliminatorcircuit bear some consideration. The rocket motor body 18 is excited atleast in part by the capacity between the electric dipole sections 22and 24 and the rocket motor body 18. This capacity, in any event, actsas a lumped capacity in shunt with the lobe eliminator 70, and must beconsidered when determining the magnitudes of the condenser 72 and theinductance coil 74.

By means of the lobe eliminator 70 between the main rocket body 18 andthe nearest section 24 of the dipole 14, radio frequency currents in thebody of the rocket 10 are reduced to a minimum, thus allowing the majorportion of the radiation to emanate from dipole 14.

Radiation patterns measured with conventional nose excitation are shownin Figures 3 and 4. The data was obtained from special high poweredsondes built into the fuze cases, and which operated on specialfrequency The overall length of the rocket from nose cap 12 to the endof the rocket 82 was about 57 /2. It will be observed that multi-loberadiation occurs, as indicated by 84 and 86 of Fig. 3, and 88, 90, and92 of Fig. 4.

Fig. 5 illustrates two radiation patterns both using a dipole sondeoperating on a given frequency range. Pattern A is the pattern in whichthe lobe eliminator of the type indicated by 70 is employed, and patternB is for the same sonde but with the lobe eliminator 70 removed. It willbe observed that pattern B is similar to the lobe pattern shown in Fig.3 except that the front lobe 94 is somewhat longer in pattern B thanlobe 86 in Fig; 3. In pattern A, most of the radiation is in a forwarddirection instead of to the rear as shown by lobe 102 of pattern A. Inaddition, it is to be noted that a single butterfly radiation pattern Areplaces the multi-lobe pattern B of Fig. 5, consisting of lobes 94 and102.

In Fig. 6 there is illustrated a radiation pattern 104 ofanother dipolesonde operating with a lobe eliminator 70 and at another frequencyrange. It will be noticed that the maximum radiation is still forward,and that the maximum forward radiation is approximately 75 from the axisof the rocket.

While lobe eliminator 70 has employed'a lumped inductance andcapacitance, a similar action might be obtained through distributedinductance and capacitance, such as a co-axial quarter wave sleevesection.

The operation of the device should be obvious from the structuredescribed. However, the operation can be summarized, in'brief, by sayingthat upon the closing of the switch 39 by screwing screw element 40 intoits holder 41, electrical contact is" made with contact element 42 sothat. the proper voltages are applied to the filament 36 and plate 38 ofoscillator tube 28. This is usually done; justprior to firing therocket.

The oscillator tube 28 then generates high frequency radiations whichare transmitted bythe dipole antenna 14. Lobe eliminator 70 acts as achoke or filter and by presenting a high impedance to any radiofrequency currents flowing from the end 24 of the dipole 14 to the bodyof the rocket motor 18, and thus reduces or minimizes the multi-loberadiation efiect.

Uponthe rocket 10 approaching a target, sufiicient energy is receivedfrom the target to operate a firing circuit, not shown, and thus firethe rocket.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is, therefore, to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. In combination, a missile having a nose section and a main bodysection, a radio frequency circuit for generating high frequencyoscillations, a dipole antenna electrically coupled to said radiofrequency circuit for radiating said high frequency oscillations fromsaid missile,-

said antenna being located between said nose section and said main bodysection and said radio frequencysaid resonant circuit filter, said meansbeing located between said antenna and said main body section.

3. The combination recited in claim 1, wherein the elements of saiddipole antenna are cylindrical and of the same diameter as the base ofsaid nose section and the main body section, whereby an uninterruptedoute surface for the missile will be provided.

4. In combination, a missile having a nose section and a main bodysection, an insulator having a chamber formed therein, a dipole antennahaving sections, one of said antenna sections being located between theinsulator and said nose section and the other of said,

antenna sections being disposed between said insulator and the main bodysection, a radio frequency circuit for generating high frequencyoscillations, said radio frequency circuit being mounted within saidchamber in said insulator and electrically connected to said antennasections, and parasitic oscillation suppressing means electricallyconnected between one of said antenna sections and said main bodysection.

5. The combination recited in claim 4, wherein said parasiticoscillation suppressing means is constituted by a resonant circuitfilter.

6. The combination recited in claim 4, wherein said parasiticsuppressing means is constituted by a resonant circuit filter having itscomponents mounted axially within the missile.

7. In a missile having a nose portion and a main body, in combination, aradio frequency circuit-in said missile for generating high frequencyoscillations, an antenna located in said nose portion and electricallycoupled to said radio frequency circuit for radiating said highfrequency oscillations, an insulating means having a chamber therein,said means being located between said nose portion and said main body ofsaid missile, and

a filter circuit electrically coupling said antenna with said main bodyof said missile and contained in said chamber, said filter circuit beingadjusted to present a high impedance to certain radio frequency currentsflowing from said antenna, whereby parasitic radiation effects of themissile are minimized.

8. In a missile having a nose portion and a main body, in combination, aradio frequency circuit in said missile for generating high frequencyoscillations, a dipole sonde consisting of an electric dipole of twosections spaced along the longitudinal axis of said missile and locatedbetween said nose portion and said main body and electrically coupled tosaid radio frequency circuit for radiating said high frequencyoscillations, an insulating means having a chamber therein, said meansbeing located between one of said dipole sections and said main body,and a filter circuit electrically coupling said dipole with said mainbody of said missile and contained in said chamber, said filter circuitbeing adjusted to present a high impedance to radio frequency currentsflowing from said dipole to said main body of said missile, whereby aradiation pattern is generated that is unaffected by the presence ofsaid main body of said missile in the electrical field generated.

9. In a missile having a nose portion and a main body, in combination, aradio frequency circuit in said missile for generating high frequencyoscillations, a dipole sonde consisting of an electric dipole of twosections spaced along the longitudinal axis of said missile and locatedbetween said nose portion and said main body and electrically coupled tosaid radio frequency circuit for radiating said high frequencyoscillations, an insulating means having a chamber therein, said meansbeing located between one of said dipole sections and said main body,and a resonant circuit filter electrically coupling said dipole withsaid main body of said missile and contained in said chamber, saidresonant circuit being adjusted to present a high impedance to radiofrequency currents flowing from said dipole to said main body of saidmissile, whereby a radiation pattern is generated that is unalfected bythe presence of said main body of said missile in the electrical fieldgenerated.

10. An arrangement as set forth in claim 9, wherein said radio frequencycircuit components are located between the sections of said dipolesonde.

11. In a missile having a nose portion and a main body, in combination,a radio frequency circuit in said missile for generating high frequencyoscillations, a dipole sonde consisting of an electric dipole of twosections spaced along the longitudinal axis of said missile and locatedbetween said nose portion and said main body and electrically coupled tosaid radio frequency circuit for radiating said high frequencyoscillations, an insulating means having a chamber therein, said meansbeing located between one of said dipole sections and said main body,and a parallel resonant circuit filter electrically coupling said dipolewith said main body of said missile and contained in said chamber, saidresonant circuit being adjusted to present a high impedance to radiofrequency currents flowing from said dipole to said main body of saidmissile, whereby a radiation pattern is generated that is unaffected bythe presence of said main body of said missile in the electrical fieldgenerated.

12. In combination, a body having two spaced portions, an insulatorhaving a chamber formed therein, a dipole antenna having sections, oneof said antenna sections being located between said insulator and one ofsaid body portions and the other of said antenna sections being disposedbetween said insulator and the other of said body portions, a radiofrequency circuit for generating high frequency oscillations, said radiofrequency circuit being contained within said chamber in said insulatorand electrically connected to said antenna sections, and parasiticoscillation suppressing means electrically connected between one of saidantenna sections and the other of said body portions.

13. In a bodyhaving at least two spaced portions, in combination, aradio frequency circuit, in said body for generating high frequencyoscillations, an antenna located between said body portions andelectrically coupled to said radio frequency circuit for radiating saidhigh frequency oscillations, an insulating means having a chambertherein, said means being located between said body portions, and afilter circuit electrically coupling said antenna with one of said bodyportions and contained in said chamber, said filter circuit beingadjusted to present a high impedance to certain radio frequency currentsfiowing from said antenna, whereby parasitic radiation eifects of saidbody are minimized.

14. In a body having two spaced portions, in combination, a radiofrequency circuit in said body for generating high frequencyoscillations, a dipole sonde consisting of an electric dipole of twosections spaced along the longitudinal axis of said body and locatedbetween said body portions and electrically coupled to said radiofrequency circuit for radiating said high frequency oscillations, aninsulating means having a chamber therein, said means being locatedbetween said body portions, and a filter circuit electrically couplingsaid dipole with one of said body portions and contained in saidchamber, said filter circuit being adjusted to present a high impedanceto radio frequency currents flowing from said dipole to one of said bodyportions, whereby a radiation pattern is generated that is unaffected bythe presence of said body in the electrical field generated.

15. In combination, a body having at least two spaced portions, a radiofrequency circuit for generating high frequency oscillations, a dipoleantenna electrically coupled to said radio frequency circuit forradiating said high frequency oscillations from said body, said antennabeing located between said body portions, said radio frequency circuitbeing positioned between the elements of said antenna, and a resonantcircuit filter between one of said antenna elements and one of said bodyportions, said filter presenting a high impedance to certain radiofrequency emanations from said antenna.

References Cited in the file of this patent UNITED STATES PATENTS2,127,088 Percival et a1 Aug. 16, 1938 2,297,512 Baeyer Sept. 29, 19422,403,567 Wales July 9, 1946 2,503,952 Laport A-pr. l l, 1950 FOREIGNPATENTS 585,791 Great Britain Feb. 25, 1947 OTHER REFERENCES Huntoon etal.: Generator-Powered Proximity Fuze," Electronics, Dec. 1945, pp.98-103 inclusive.

